you could look at drumkv1. You can load wave samples and link them to a note.
http://drumkv1.sourceforge.net/drumkv1-index.html

There also Highlife of discoDSP. It has been ported to juce and can be loaded als lv2 plugin.
It's part of Distrho-project. You can grab it overthere, or compile from source if you want to.
It contains also lot's of other verygood plugins and ports(stuff from TAL Audio, noisemaker etc)

Just for your information Highlife does not work and is no longer supported. There is also samplev1 to load samples, or you could convert them to SFZ and play them with linuxsampler. To convert to SFZ use a text edtior (SFZ is a text based format), or synthclone (tutorial http://www.remastersys.com/forums/index.php?topic=3144.0) , or the makesfz.sh script (see http://www.remastersys.com/forums/index.php?topic=1951.0)